1. Field of the Invention
The invention relates to a cell structure of a plasma display panel.
2. Description of the Related Art
Recent years, a plasma display panel (referred to xe2x80x9cPDPxe2x80x9d hereinafter) of a surface discharge scheme AC type as an oversized and slim display for color screen has been received attention, which is becoming widely available.
FIG. 8 is a schematically plane view of a conventional cell structure of such PDP. FIG. 9 is a sectional view taken along the Vxe2x80x94V line of FIG. 8. FIG. 10 is a sectional view taken along the Wxe2x80x94W line of FIG. 8.
In FIG. 8 to FIG. 10, on the backside of a front glass substrate 1 to serve as a display screen of the PDP, there is sequentially provided with a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2); a dielectric layer 2 covering the row electrode pairs (Xxe2x80x2, Yxe2x80x2); and a protective layer 3 made of MgO which covers a backside of the dielectric layer 2.
The row electrodes Xxe2x80x2 and Yxe2x80x2 respectively consist of wider transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 each of which is formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xbxe2x80x2 and Ybxe2x80x2 each of which is formed of a metal film, complementary to conductivity of the transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged opposing each other with a discharge gap gxe2x80x2 in between, and alternate in the column direction to form a display line (row) L on a matrix display screen.
A back glass substrate 4 faces the front glass substrate 1 with a discharge space S, filled with a discharge gas, in between. The back glass substrate 4 is provided with a plurality of column electrodes Dxe2x80x2 arranged to extend in a direction perpendicular to the row electrode pairs Xxe2x80x2 and Yxe2x80x2; band-shaped partition walls 5 each extending between the adjacent column electrodes Dxe2x80x2 in parallel; and a red phosphor layer 6(R), green phosphor layer 6(G) and blue phosphor layer 6(B) which respectively overlay side faces of the partition walls 5 and the column electrodes Dxe2x80x2.
In each display line L, discharge cells C are divided by the partition walls 5 in the column direction, and respectively formed at intersections of the column electrodes Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2) in the discharge space Sxe2x80x2.
In the above PDP, an image is displayed as follows:
First, through address operation, discharge (opposite discharge) is generated selectively between the row electrode pairs (Xxe2x80x2, Yxe2x80x2) and the column electrodes Dxe2x80x2 in the respective discharge cells C, to scatter lighted cells (the discharge cell C formed with wall charge on the dielectric layer 2) and nonlighted cells (the discharge cell C not formed with wall charge on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the address operation, in all the display lines L, the discharge sustain pulse is applied alternately to the row electrode pairs (Xxe2x80x2, Yxe2x80x2) in unison, and thus discharge (surface discharge) is produced in the lighted cells on every application of the discharge sustain pulse.
In this manner, the surface discharge in each lighted cell generates ultraviolet light, and thus the red phosphor layer 6(R) and/or the green phosphor layer 6(G) and/or the blue phosphor layer 6(B) each formed in the discharge cell C are excited to emit light, resulting in forming the display screen.
For the PDP as configured above, displaying images with definition needs to reduce a size of each discharge cell C to increase the number of pixels each made up of the phosphor layers 6(R), 6(G) and 6(B) as a unit.
However, fulfilling such a demand for displaying images with high definition, if each discharge cell C is reduced in size,_it causes a reduced surface area in each of the phosphor layers 6(R), 6(G) and 6(B) of the discharge cells C. This produces another problem of reduction in luminance.
In the PDP, the maximum length of extension of each of the transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 of the respective row electrodes Xxe2x80x2 and Yxe2x80x2 onto the discharge cell C, corresponds to approximately half the length of a longitudinal side of the discharge cell C. Therefore, when each size of the discharge cell C is reduced in order to achieve the high definition image as described above, the transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 of the row electrodes Xxe2x80x2 and Yxe2x80x2 are also reduced in length. This produces problems of reduction in efficiency of light emission and further reduction in luminance.
As described above, if each size of the discharge cells C is reduced to increase the number of pixels for the high definition image, this increases the number of partition walls 5 defining the discharge cells C and the row electrode pairs (Xxe2x80x2, Yxe2x80x2), and in turn increases an area of portions reflecting ambient light incident from the panel surface of the PDP. As a result, a problem in that the reflected light promotes reduction in contrast of an image is produced.
The present invention has been made to solve the above problems associated with the conventional plasma display panel.
It is therefore a first object of the present invention to provide a plasma display panel which is capable of preventing reduction in luminance associated with increase in definition of images.
It is a second object of the present invention to provide a plasma display panel which is capable of preventing reduction in contrast of an image due to reflection of ambient light incident from the panel surface.
To attain the first object, a plasma display panel according to a first invention includes a plurality of row electrodes extending in the row direction on a backside of a front substrate and arranged in the column direction, and a plurality of column electrodes extending in the column direction on a surface of a back substrate facing the front substrate with a discharge space in between and arranged in the row direction. Such plasma display panel is characterized in that the row electrode has an electrode main body portions extending the row direction and a plurality of protrusion electrode portions extending in the column direction and arranged along the electrode main body portions to intersect and connect with the electrode main body portions. And also, an end of the protrusion electrode portion of the row electrode opposes to an end of the protrusion electrode portion of the row electrode adjacent thereto, with a required gap in between. And then, a unit light emitting area is formed in each discharge space between the back substrate and a section of the protrusion electrode portions which are paired by the two opposing ends of the protrusion electrode portions with the required gap in between.
In the plasma display panel according to the first invention, the row electrodes constituting the unit light emitting area together with the column electrode at an intersecting section of the row electrodes and column electrode, are respectively provided with a plurality of protrusion electrode portions each intersected with and connected to the electrode main body portion extending in the row direction, for each unit light emitting area. Each of the unit light emitting area is formed at a portion where the paired protrusion electrode portions of the adjacent two row electrodes are opposed, in the discharge space.
According to the first invention, hence, the protrusion electrode portion is intersected with and connected to the electrode main body, to extend from the electrode main body in the opposite direction of the mate of the paired protrusion electrode portions. For this reason, each unit light emitting area is formed not only between the two electrode main bodies connected to the pair of protrusion electrode portions but also on each opposite side of the pair of electrode main bodies. Therefore, increase in width of each unit light emitting area in the column direction increases an area of emission.
Thus, upon the surface discharge between a pair of protrusion electrode portions, the amount of light emission in each unit light emitting area is increased to prevent the reduction of luminance associated with high definition of a screen.
In addition, efficiency of light emission is increased as a length of the protrusion electrode portion is increased in the column direction, which prevents reduction in luminance associated with high definition of a screen.
To attain the first object, the plasma display panel according to a second invention is characterized, in addition to the configuration of the first invention, in that the protrusion electrode portions of the row electrode are alternately paired with protrusion electrodes of two row electrodes on both sides of the row electrode to form the unit light emitting areas.
According to the plasma display panel of the second invention, the protrusion electrode portions arranged along the row electrode are alternately paired with the protrusion electrode portions of row electrodes on both sides of the row electrode. As a consequence of this, the unit light emitting areas formed at portions opposing the above pairs of protrusion electrode portions in the discharge space are situated at positions alternately shifting in the column direction along the row direction.
Then, a pixel is made up of the three unit light emitting areas of the thus arranged unit light emitting areas which are located at contiguous positions where a triangle is formed by connecting the centers of the three unit light emitting areas.
To attain the first object, the plasma display panel according to a third invention is characterized, in addition to the configuration of the first invention, in that the protrusion electrode portion of the row electrode extends longer from one side of the electrode main body portion than from the other side. And also, ends of the longer extensions of the respective protrusion electrode portions of the adjacent row electrodes make a pair, opposing each other with the required gap.
According to the plasma display panel of the third invention, each unit light emitting area is formed in a portion of the discharge space opposing the longer extensions of the protrusion electrodes protruding from the sides of the electrode main bodies of the two adjacent row electrodes toward the midpoint between the electrode main bodies, and a portion of the discharge space opposing the shorter extensions of the protrusion electrodes protruding from the electrode main bodies of the two adjacent row electrodes in the opposite direction from each other.
Hence, an area of emission of each unit light emitting area is increased by the shorter extension of the protrusion electrode portions extending in the discharge space in the opposite direction from the mate of the paired row electrodes, resulting in preventing reduction in luminance in the column direction.
To attain the second object, the plasma display panel according to a fourth invention is characterized, in addition to the configuration of the first invention, in that a light absorption layer not reflecting light is formed on the front face of the electrode main body portion of the row electrode.
According to the plasma display panel of the fourth invention, since the light absorption layer overlays the faces on the display surface side of the electrode main bodies which occupy the area of the image display surface of the panel except for the openings of the unit light emitting areas, ambient light incident through the front glass substrate is absorbed by the absorption layer. This prevents reflection of the incident light and reduction in contrast on the screen due to the reflection.
To attain the first object, the plasma display panel according to a fifth invention is characterized, in addition to the configuration of the first invention, in that the unit light emitting areas are defined by a partition wall made up by a vertical wall portion extending in the column direction and a transverse wall portion extending in the row direction which are disposed between the front substrate and the back substrate.
According to the plasma display panel of the fifth invention, the discharge space between the front substrate and the back substrate is defined in matrix form in the row direction and the column direction for each unit light emitting area by the transverse walls and the vertical walls of the partition wall.
This prevents a false discharge from being generated by occurrence of interference between the discharges of the unit light emitting areas adjacent to each other in the row direction and the column direction, resulting in high definition of a screen.
To attain the first object, the plasma display panel according to a sixth invention is characterized, in addition to the configuration of the fifth invention, by further including a dielectric layer formed on the backside of the front substrate to overlay the row electrodes, and in that an additional portion is formed on a portion of the dielectric layer facing the transverse wall, to protrude toward the transverse wall portion to shield the adjacent unit light emitting areas from each other in the column direction.
According to the plasma display panel of the sixth invention, the additional portion of the dielectric layer shields the adjacent unit light emitting areas from each other in the column direction. This prevents a false discharge from being generated by occurrence of interference between the discharges of the adjacent unit light emitting areas, resulting in high definition of a screen.
To attain the first object, the plasma display panel according to a seventh invention is characterized, in addition to the configuration of the first invention, in that the unit light emitting areas are defined by a band-shaped partition wall extending in the column direction between the front substrate and the back substrate.
According to the plasma display panel of the seventh invention, the band-shaped partition wall extending in the column direction defines a border between the adjacent unit light emitting areas in the row direction.
To attain the second object, the plasma display panel according to a eighth invention is characterized, in addition to the configuration of the fifth or seventh invention, in that a light absorption layer not reflecting light is formed on the face on the front substrate side of the partition wall.
According to the plasma display panel of the eighth invention, since the light absorption layer overlays the face on the display surface side of the partition wall which occupies the area of the image display surface of the panel except for the openings of the unit light emitting areas, ambient light incident through the front glass substrate is absorbed by the absorption layer. This prevents reflection of the incident light and reduction in contrast on the screen due to the reflection.
The plasma display panel according to a ninth invention is characterized, in addition the configuration of the first invention, in that the unit light emitting areas are disposed to differ in alignment in the column direction from each other in each two adjacent unit light emitting area columns by half of length of the unit light emitting area in the column direction, and respectively formed therein with phosphor layers having three colors arranged in a sequence in the row direction, and a pixel is comprised of the three unit light emitting areas of the three respective colors arranged in a delta form along the two adjacent display lines.
According to the plasma display panel of the ninth invention, a pixel is made up of the three adjacent unit light emitting areas staggered from the neighboring unit light emitting area in the column direction and colored in the three primary colors.
The plasma display panel according to a tenth invention is characterized, in addition to the configuration of the fifth invention, by further including a dielectric layer formed on the backside of the front substrate to overlay the row electrodes, and in that an additional portion is formed on a portion of the dielectric layer facing the vertical wall portion of the partition wall above the electrode main body portion, to protrude toward the vertical wall portion to be in contact with the vertical wall portion.
According to the plasma display panel of the tenth invention, the additional portion formed on the dielectric layer, overlaying the row electrodes, to be in contact with the vertical wall of the partition wall prevents a false discharge from being generated between the adjacent unit light emitting areas.
The plasma display panel according to an eleventh invention is characterized, in addition to the configuration of the seventh invention, by further including a dielectric layer formed on the backside of the front substrate to overlay the row electrodes, in that an additional portion is formed on portions of the dielectric layer above the electrode main body portion, to protrude toward the partition wall portion to be in contact with the partition wall.
According to the plasma display panel of the eleventh invention, the additional portion is formed on the dielectric layer, overlaying the row electrodes, to be in contact with the partition wall. Such additional portion prevents a false discharge from being generated between the adjacent unit light emitting areas.
These and other objects and advantages of the present invention will become obvious to those skilled in the art upon review of the following description, the accompanying drawings and appended claims.